Yesterday morning the low hit 14F and when I started the teener the generator light stayed on solid & bright red. I thought I had heard a thump sound as I backed out of the driveway and since I was still in a caffiene-deprived state I figured I'd probably broken the belt and I just parked it and borrowed another car to get to work.

Last night I went out to work on the problem and when I start up the car the generator light goes out just like it should. I finally remember how easy it is to check the belt and sure enough the belt is just fine. Since I don't have a garage I figure I'm not staying out in the cold to work on a problem that isn't there so I just park it for the night and wait to see what the morning brings.

This morning the temp hit the same mark and I've got the same problem. I figure this has to be temperature related so I drive the car anyway and take the slow residential streets so that I can generate as much heat as possible. As I'm driving I notice that the stock voltmeter is showing about 11.5 volts. After about 6 miles the generator light suddenly goes out and the voltmeter jumps up to 13.5 volts.

Anybody seen this kind of thing before and have any idea what I should be looking for?

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As long as I'm asking about charging system issues - on my son's 1975 VW Bus I've got an issue where the battery slowly loses charge, but it isn't obvious until one morning you don't have enough power to crank it and produce a good spark so it won't start. The only indication I've got is that when you turn on the blinkers you can see the alternator light flash in time with the blinkers. I've added a separate grounding cable to run from the battery back to the engine, but this didn't change it. Any ideas?

how old is your battery?
moisture inside the alternator (read ICE when below freezing)?

just a few wild guesses,
Andy

frozen belt that's a little too loose ? pulley slips until engine warms it enough to be flexible?

Water inside the mechanical voltage regulator? Freezes and keeps the battery from charging... Resistance in the warning light circuit, or an incorrect bulb in the light?

--DD

last time this happened to me it was a bum alternator... it'd charge either not all the time, or not enough, and eventually flatten the battery. bad regulator could do it too, unless it's internally regulated in which case you get a 2-for-1 ... (i know nothing 'bout busses ...)

What is the correct bulb wattage?

That's what so mysterious about this. Both the voltage regulator and the alterntor have been replaced in the last few years. The battery is a fairly new Optima that tests out fine as well. Buses are basically just like 14s in this regard. The VR is mounted to the firewall, but is even the same part # (I think - it looks the same anyway). On the STF I picked up the tip of running a separate grounding wire from the point on the body where the battery ground connects back to the engine. The guy said that in his experience this solved problems with inadequate charging. It's too soon to tell if the extra wire has actually fixed the problem, but I was hoping that after this the symptom with the alternator light would go away. Is there a way to check what the battery is getting using a regular voltmeter?

I'll have to check into the bulb thing. Since this bus at one time followed the Greatful Dead around the country, there's no telling what they did to it. When we got it there was a Type1 engine in it (and it's supposed to be a Type IV).

Well it turns out that the issues on both cars were tied to the same part - the voltage regulator. I borrowed a VR from my son's 73 and the problem on my car went away. Today I put in a new VR in the bus and the alternator light no longer flashes when you put the turn signals on.

Funny thing about the bus - the VR I pulled out is a Bosch 0 190 600 016 which is for a 70-74. The one I put in today is a 0 190 601 006 whis for a 72-79 bus. The guys at BAP say that the VR for a 75 bus is the same as for a 73 914 so if you are changing yours it might be wise to check the part number carefully when they hand you that yellow box & make sure it's the same as what you've got.